Electrolytically deposited iron



Patented Sept. 22, 1942 UNITED STATE ELECTROLYTICALLY DEPOSITED IRONJohn L. Young,

Pittsburgh, Pa., assignor, by

. mesne assignments, to Plastic Metals, Inc., a

corporation of New York No Drawing.

Application September 1, 1938, Serial No. 227,972

'1 Claim. (01. 204-112) This invention relates to electrolyticallydeposited bodies and methods of production of such bodies. Its object isthe production of bodies of superior quality and of enhanced utility.

In an application for Letters. Patent of the United States, Serial No.50,003, filed November 15, 1935, by John L. Young and Allen CameronJephson now Patent Number 2,128,389 of August 30, 1938; theelectrolytical deposit of a sheet of iron is described; and to thedeposited sheet certain valuable characteristics and adaptabilities areimputed. These characteristics and adaptabilities are due to the factthat the component crystals of the so-developed sheet extend'in adirection perpendicular -to the surface upon which the deposit is made,and to the further fact that small amounts of iron oxide are occluded atthe grain boundaries. The sheet may by heat treatment be rendereddrawable, without destruction of its characteristic and desirablecrystalline grain structure; and it presents a surface that isrelatively inert, not readily susceptible to chemical reaction, superiorin ability,

to afford union with an applied material, superior in its responsivenessto welding, soldering, tinning, and to enamel coating operations, andsuperior in its ability to receive and carry coatings of lacquer and ofpaint.

I am one of the above named joint applicants. My present furtherinvention is an improvement upon the invention of that earlierapplication; an improvement, by virtue of which the valuable featuresand characteristics already recognized may be provided and enjoyed inlarger measure.

It is well known to the industry that, by the process of electroplating,a given metal may be derived from a source in which it is found inrelative impuritychemical combination or physical association with othersubstances-and -deposited in substantial purity upon a cathode.Explanation is, in the earlier application, afforded that in suchmannera deposit may be formed whose grains are of iron, a deposit thatis free (if-impurities of a reducing nature and that carries, occludedat the grain boundaries, small quantities of iron oxide (or hydroxide).The procedure of my present invention, otherwise such as that justindicated, involves thedevelopment at the grain boundaries of thedeposit, not of small quantities of iron oxide alone, of smallquantities of iron oxide in association with'silica. These combinedoxides, so present,

aflord a product that possesses in superior degree the good features andcharacteristics indicated-due, as I believe, to a superior toughness,

but

hydrogen;

strength, and inter-grain bonding of these com bined oxides.

Electrolytic iron has been found to be extremely ductile, but to lackresistance to shock. 'As an illustration, I prepared a number of shotgunshells, using a paper shell with metal end;

The metal end was made of electrolytic iron. I found that, while theseshells could be fabricated satisfactorily, when the loaded shell wasplaced in the gun and fired the metal end split. This quality ofelectrolytic iron has been previously mentioned in The Metal Iron,Cleaves and Thompson. I believe that this lack of resistance to shock iscaused by the iron oxide between the grains of iron being brittle,and'lacking adhesion to the iron crystals. I have improved thisresistance to shock greatlyby adding impurities at the grain boundaries,so that during heating a strong welding agent, flux,

In the practice of my invention I may employ in the electrolytic cell astripping cathode, a solu- 'ble anode of iron, and an electrolyte suchin composition as to afford a deposit free of impurities of a-reducingnature. The electrolytic operation will be conducted at such temperatureand the current strength will be such as to effect the desired depositof iron upon the cathode. These matters ofelectrolyte composition and ofconditions of operation are within the knowledge of the art. To theelectrolyte silica is added in suitable form (within the knowledge ofthe art),

to effect simultaneously'with the iron a deposit I of silica. Thecrystalline grains of the deposited iron will be found to extend in adirection perpendicular to the surface of the cathode. The deposit willbe found to be substantially free of but at the grain boundaries will befound moisture, iron hydroxide, and some form of silica;

The sheet so deposited may be stripped from the cathode and then heat-treated in non-oxidizing atmosphere. The silica combines with the ironoxide, forming an iron silicate at the grain boundary which essentiallyholds the needle structure obtained by electrodeposition, even thoughthe sheet is heated above the upper critical point whererecrystallization should takeplace.

By this means a. sheet of iron is. obtained which can be heat-treated toobtain its deep drawing properties at apoint above the upper criticalpoint. This feature is of special advantage in commercial temperaturesare subject to considerable fluctuation and where the upper criticaltemperature is or slag will be formed.

work, where furnace liable to be exceeded; The effect, in such case,would be a great reduction in ductility, if the sheet were free ofsilica, or its equivalent.

While I have specified silica, I am in fact disclosing, in this and in acompanion application, Serial No. 222,297, a method of holding theelectrolytic structure of a sheet when heating above the upper critical,which consists in causing the While it is understood that this envelopearound the electrolytic crystals would in practise be made as thin aspossible to attain the desired result, for purposes of demonstration,usingsilicate, high pH, and low current density, a material can be madewhich will contain sufficient slag distributed between the electrolyticcrystals to give something of the appearance under the microscope of aknobbled iron.

In the finished sheet the combined iron oxide and silica (or equivalentoxide) will be found to have effect superior to that of iron oxide sopresent alone. The response of the sheet to deep-drawing dies is morecomplete; it will endure greater strains without rupture; and thesurface is of even better condition for the reception of and for theadherence of tin, glass, lacquer, or paint. face renders the sheetpeculiarly suitable as solder,

3 The inertness of surmaterial from which to shape metal containers.

The practice of the invention does not require the use of a solubleanode. The art knows how,

variously to efiect the deposit of iron free of association with anyreducing impurity, and, as has been said, the concomitant deposit ofsilica, once suggested, may be accomplished within the knowledge of theart. In the choice of the electrolyte solutions of organic salts areordinarily to be avoided, since, manifestly, under ordinary conditions,their use would prevent the intergranular deposit of the desired oxides.

It will have been remarked that the good and valuable characteristics ofthe electrolytically deposited sheet of my invention are not whollyattendant upon or limited to the peculiar crystaL line structure of anelectrodeposited sheet, and are such as may be enjoyed whether the sheetbe shaped between dies or not. That is to say, the sheet is of suchsurface character and-quality as to render it peculiarly suited forvarious welding, soldering, and coating operations. It follows that, ifa body of metal otherwise produced (say a rolled sheet of steel) beelectroplated with iron in the manner described, and a deposit beproduced in which a small deposit of combined iron oxide and of silica(or equivalent oxide) beoccluded at the grain boundaries, the articleproduced will be of superior quality for subsequent welding, soldering,and coating operations. I mean, therefore, to include within the fieldof my broader claims a metallic article that possesses superficiallyonly the character of electrolytically deposited iron with iron oxideand silica together occluded at the grain boundaries.

I claim as my invention:

An electrolytically deposited sheet of iron 5 capable of maintaining itsfine-grained electrolytic structure when heated to a temperatureexceeding the upper critical, in which the crystalline grains of thedeposit are enveloped in a slag of iron oxide and silica.

JOHN L. YOUNG.

